1. Field of the Invention
The present invention relates to an exposure device for forming patterns on a surface of a flat-sheet material, including a substrate for an electronic circuit, a glass substrate for an LCD and a glass element substrate for a PDP.
2. Description of the Related Art
In general, substrates for electronic circuits or printed circuits are applied to portable phones or various types of PCs. On a substrate of this type, multiple fine patterns, lands and via-holes tend to be formed with great precision. In order to follow this trend, an exposure device which is used in an exposure process for forming patterns needs to possess a technique for generating high-intensity and precise-collimated light beams.
A general type, that is, contact or projection type exposure device is required to handle many different types of substrates in a short period. Such an exposure device needs to contain masks to form patterns. Accordingly, multiple different masks are prepared depending on the types of substrates to be processed. However, those masks are hard to prepare, exchange or maintain, thus making it difficult to treat many different substrates efficiently.
Because of this disadvantage, interest is growing in a direct type exposure system and a device incorporating this system. This direct type exposure system transfers patterns from CAD data to a substrate by means of light beams, so that masks are unnecessary (see JP A 2006-113413, JP A 2006-343684 and JP A 2006-337475). However, a typical direct exposure device tends to have a low reaction speed in forming patterns, because its light source is a laser of a short wavelength such as 405 nm. Hence, efficient direct type devices have been highly in demand.
In addition to the inefficient exposure operation as described above, a typical direct exposure device involves a cost increase. This is because it is equipped with many spatial light modulation elements for treating large-size substrates. If high-intensity light beams are irradiated on those many spatial light modulation elements, then many light sources are required, thus leading to the increase in the material costs.
The direct type exposure device of JP A 2006-343684 or JP A 2006-337475 is designed to address this disadvantage. Specifically, this device has seven low-illumination UV lamps and optical fibers. Further, the rays outputted from the lamps are supplied by the optical fibers to one or more optical systems. Moreover, as shown in FIG. 6 of those two documents, in both devices, the input end of the fiber is positioned at the secondary focal point of the elliptic mirror. However, the illumination of the seven UV lamps is difficult to adjust, thus making it almost impossible to control the ray in accordance with the photo-sensitive property of an object to be processed.
Taking the above description into account, the present invention has been conceived. An object of the present invention is to provide a direct type exposure device which works efficiently. An additional object of the present invention is to present a direct type exposure device which has a few optical sources and many digital micro-mirror devices (DMDs) functioning as spatial light modulation devices.